A low rate of hepatitis B virus vaccine breakthrough infections in Mongolia

Authors

  • Samreen Ijaz,

    Corresponding author
    1. Department of Virology, Royal Free and University College Medical School, London, United Kingdom
    Current affiliation:
    1. Virus Reference Department, Centre for Infections, Health Protection Agency, 61 Colindale Avenue, London, NW9 5HT, United Kingdom.
    • Department of Virology, Royal Free and University College Medical School, London, UK.
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  • Janchiv Khulan,

    1. Institute of Public Health, Ministry of Health, Ulaanbaatar, Mongolia
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  • Sara L. Bissett,

    1. Department of Virology, Royal Free and University College Medical School, London, United Kingdom
    Current affiliation:
    1. Virus Reference Department, Centre for Infections, Health Protection Agency, 61 Colindale Avenue, London, NW9 5HT, United Kingdom.
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  • R. Bridget Ferns,

    1. Department of Virology, Royal Free and University College Medical School, London, United Kingdom
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  • Pagbajabyn Nymadawa,

    1. Institute of Public Health, Ministry of Health, Ulaanbaatar, Mongolia
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  • Richard S. Tedder

    1. Department of Virology, Royal Free and University College Medical School, London, United Kingdom
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Abstract

A nation-wide hepatitis B virus (HBV) immunization program of all newborn babies was launched in Mongolia in 1991. However, the continuation of clinical icteric viral hepatitis infections in children led to the investigation to determine whether HBV breakthrough infections were occurring and if any were due to hepatitis B surface antigen (HBsAg) mutants. Hepatitis A virus (HAV) infections accounted for most of these cases with 3% of the jaundiced children shown to have acute hepatitis B. Hepatitis B vaccine protection was 93% against HBV infection and 97% against HBV carriage. A G145A “escape mutant” was found in one HBV carrier child only. Anti-HBs levels, however, were low with 85% having titers less than 100 IU/L, 46% of whom had levels less than 10 IU/L. The results from this study demonstrate that the HBV immunization program in Mongolia provides an effective level of protection. However, continued surveillance of breakthrough infections and close monitoring of “vaccine escape” mutants is required. J. Med. Virol. 78:1554–1559, 2006. © 2006 Wiley-Liss, Inc.

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